HR: 1330h
AN: OS23A-09    [Abstracts]
TI: Influence of ENSO-Related Wind Stress Variability on the Coastal Upwelling off Peru
AU: * Huaringa, E E
EM: huaringa@usp.br
AF: Instituto Oceanográfico da Universidade de São Paulo, Pça. do Oceanográfico,191, São Paulo, SP 05508-120 Brazil
AU: Campos, E J
EM: edmo@io.usp.br
AF: Instituto Oceanográfico da Universidade de São Paulo, Pça. do Oceanográfico,191, São Paulo, SP 05508-120 Brazil
AU: Lentini, C A
EM: lentini@io.usp.br
AF: Instituto Oceanográfico da Universidade de São Paulo, Pça. do Oceanográfico,191, São Paulo, SP 05508-120 Brazil
AB: The Eastern Tropical and Subtropical Pacific, particularly the coastal region off the western South America, is negatively affected by the El Niño-Southern Oscillation (ENSO) events. The rise of coastal sea temperatures due to the weakening of coastal upwelling causes the reduction of important fish stocks and other coastal resources of economical significance, especially the sardine and anchovy populations. Here, variability in the intensity of upwelling along the Peruvian coast is studied using monthly means of the ERS-1 and ERS-2 scatterometer wind stress. In the study area, the Trade Winds blow predominantly parallel to the coast, making the upwelling system highly sensitive to variability in the intensity of the wind stress. On its turn, the wind stress intensity is expected to suffer strong variation during ENSO periods. In our ongoing work we try to understand the relationship between coastal upwelling and different ENSO events in the 1991-2000 decade. In this period, two warm events where observed, the relatively weaker 1991-1994 and the stronger 97-98 El Niños. In both cases we found that in the region from 12°S to 3°S, the intensity of alongshore wind stress is reduced considerably, with the coastal upwelled waters being replaced by warmer waters. On the other hand, in the region between 12°S and 19°S the coastal upwelling maintains its intensity because only the cross-shore component of the wind stress was reduced. With respect to the two cold events, the 1996-1997 and the 1998-2000 La Niñas, the intensity of the alongshore windstress was higher than the climatological values. This resulted in more intense upwelling in the entire region.
UR: http://www.labmon.io.usp.br
DE: 4279 Upwelling and convergences
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly